The present invention relates to measuring the thermodynamic sulfur activity in a process environment. In particular, the present invention includes a method and a sensor to measure sulfur activity.
In many processes, for example in the refining of crudes or in sour gas production wells, there is a significant need to measure the thermodynamic activity of sulfur which is established in the environment by the interplay of the various sulfur containing corrosive species. Sulfur activity is a well known measure of the available sulfur for reaction (see e.g., "An Analysis of the Phase Equilibria in the Fe-FeS System", Metallurgical Transactions B, p. 37-41, Vol. 6B, March 1975). To provide operational flexibility in these environments, it is of great interest to predict the rates of corrosion. Typically, these environments exhibit temperature ranges 150.degree. F. to 1000.degree. F. The thermodynamic activity of sulfur can be used as a generalized index of corrosivity. Thus, if the sulfur activity can be directly measured by means of a sensor, this will provide a determination of corrosivity prediction.